1. Field of the Invention
The present invention relates to a recording device that records video data and the like onto a removable medium.
2. Background of the Related Art
Digital recorders have recently been developed and commercialized for digitally recording audio and video data (AV data) of broadcast programs transmitted by digital broadcasting services. A digital recorder is typically used as being connected via an IEEE 1394 interface to a digital TV (hereafter, a “DTV”) or the like that receives digital broadcasts. The IEEE 1394 enables AV data etc., requiring a real-time transfer, to be transferred between devices using an isochronous transfer method, and enables control data to be transferred between devices using an asynchronous transfer method. For the transfer of control data, AV/C commands specified by the 1394 Trade Association are used.
The AV/C commands are a command set used by an AV device for remote-controlling another AV device connected via the IEEE 1394. Here, a device such as a DTV that performs remote-control, i.e., a device that issues a command, is referred as a “controller”, where as a device such as a digital recorder that is remote-controlled, i.e., a device that receives a command, is referred to as a “target”. Examples of AV/C commands used by the controller include: commands to control the target's functions including playback and recording of AV data etc. and writing and reading of information about the AV data; and commands to query the current status of the target.
These AV/C commands can realize various applications, one of which is described below. The DTV issues anAV/C command to the digital recorder, so as to read various information about AV data of each broadcast program, such as a title name, recording date and time, and program outline. The DTV arranges and displays the read information, so that the user can select a broadcast program he or she wants by referring to the displayed information. Upon receipt of a user selection of a broadcast program, the DTV issues an AV/C command to instruct the digital recorder to play back AV data of the broadcast program.
The following describes one example of the processing flow of this application.
The DTV receives AV data of broadcast programs transmitted via digital broadcasting services, and obtains information about AV data of each broadcast program, such as a title name, recording date and time, and program outline from an EPG (electric program guide) transmitted together with the AV data. Such information about AV data of each broadcast program is hereafter referred to as “program information” in this specification. The DTV then transfers, to the digital recorder, the received AV data of broadcast programs and the obtained program information, together with an AV/C command that instructs the digital recorder to write them therein.
Upon receipt of this AV/C command, the digital recorder records the transferred AV data and the program information onto its recording medium.
After the digital recorder completes the recording, the DTV issues an AV/C command that instructs the digital recorder to read all program information stored in the recording medium.
Upon receipt of this AV/C command, the digital recorder transmits all program information stored in the recording medium to the DTV.
The DTV receives the program information, and generates a program list listing title names, program outlines, etc., of broadcast programs, based on the received program information. The DTV then displays the program list for user selection.
Upon receipt of a user operation selecting one broadcast program in the program list, the DTV specifies AV data of the broadcast program. Then, the DTV instructs the digital recorder to read the AV data of the broadcast program. The DTV receives the AV data of the broadcast program from the digital recorder, and plays back the received AV data.
In the above application, a problem may arise when the recording medium of the digital recorder is an optical disc. Optical discs of different types often employ different data formats. The problem is therefore that compatibility may not be maintained between the DTV and a certain type of optical disc.
Here, the data format of an optical disc defines items of program information that can be recorded on the optical disc, a recording area of each item, and a size of a recording area of each item. As examples, a DVD-RAM and a DVD-RW employ the DVD Video recording format, where as a DVD-R and a DVD-ROM employ the DVD Video format.
The above problem of incompatibility occurs when the DTV, and an optical disc loaded in the digital recorder employ different data formats and items of program information defined by the data format of the DTV are not defined by the data format of the optical disc. In this case, the digital decoder cannot record certain items of program information onto the optical disc even if instructed to do so by the DTV with the use of an AV/C command. As a result, the digital decoder cannot read such items of program information from the optical disc at the time when instructed to do so by the DTV with the use of an AV/C command. Accordingly, the DTV fails to obtain and display these items of program information.
In particular, optical discs with a large capacity that have been developed in recent years employ the data format defining various items of data that are not defined by the existing data formats. Therefore, the above problem of incompatibility is even more serious between devices complying with such large-capacity optical discs and the existing optical discs. To solve this problem, one method is to enable the DTV to identify the data format of an optical disc currently loaded in the digital recorder and switch AV/C commands to be issued to the digital recorder in accordance with the identified data format. With this method, the DTV may suffer from degraded development efficiency of applications.